The authors of Mac Defender have come out with a variant which they are calling MacGuard, according Ed Bott, the blogger who has been driving the story.

After several days of pretending the problem didn't exist, Apple yesterday issued advice to users regarding the threat and announced that an upcoming OS X update would seek out and remove it. It's hard to believe that Apple would be naive enough to think that would be the end of it, but that may be the case.

Microsoft and dozens of PC software companies could tell Apple that generic solutions to threats such as these are extremely hard to construct, since they don't do anything malicious to the computer in the general sense of the term. All they do is display fancy fake scans and demand money. It's fairly easy for an experienced human to recognize these for what they are, but it's quite hard for software to do so without a significant chance of false positives. Indeed, PC security products have poor detection rates on this class of malware.

By issuing an update for Mac Defender has Apple created a precedent? If new variations of it, and new threats, start showing up every few days, will they issue updates in reaction? This is clearly a losing strategy.

The way it's handled on PCs is that security suites detect a high, if inadequate, percentage of rogue threats, but much of the burden rests with the user to know a scam when they see it. As hard as it has been to train PC users for this job, Mac users will be even harder to train.